1. Field of the Invention
The present invention relates generally to apparatus for facilitating the movement of a plunger of a syringe through a barrel of the syringe and, more particularly, to hand-held, hand operated apparatus that facilitate the movement of a plunger through a syringe barrel. More specifically, the present invention relates to hand-held apparatus with scissor grip type leveraged triggering systems that force a plunger of a syringe through the length of the barrel of the syringe.
2. Background of Related Art
Apparatus that facilitate the ejection of fluids from syringes are well known. Such apparatus are often referred to as fluid delivery devices or power syringes.
Conventionally, fluid delivery devices have been used to inject liquids, such as contrasting media (e.g., dyes, carbon dioxide, etc.) and medicines into patients. With many fluid delivery devices, the rate at which a fluid is injected into a patient's body may be controlled. While some of these devices are automated, others may be manually operated.
Due to the increase in delivery force provided by fluid delivery devices, such devices are particularly useful for injecting high viscosity fluids, which would otherwise be difficult, if not impossible, to inject by forcing one's thumb against the plunger of a conventional hand-held syringe.
Some hand-held power syringes, such as that disclosed in U.S. Pat. No. 5,330,074, issued to Wirsig et al. (hereinafter “the '074 Patent”), include ratcheting type mechanisms to assist a user in applying force to a plunger of the syringe. Ratcheting mechanisms are, however, often complex and, consequently, add to the manufacturing costs of such hand-held power syringes.
Other hand-held fluid delivery devices include handles with a fixed member and a movable member associated therewith. In one example of such a syringe, disclosed in U.S. Pat. No. 6,059,759, issued to Lampropoulos et al. (hereinafter “the '759 Patent”), the movable member may be slidingly secured to the fixed member. A plunger is forced into a syringe barrel as a user squeezes the handle members toward one another. Nonetheless, such a syringe only assists the user in forcing the plunger into the syringe barrel by transferring the location where force must be applied and increasing the area of a member to which force must be applied. Alternatively, the ends of the movable member and the fixed member of the handle may be pivotally secured to one another, as described in U.S. Pat. No. 6,024,728, issued to Schulz (hereinafter “the '728 Patent”). In either event, an upper end of the movable member either directly or indirectly engages a plunger of the syringe. Upon squeezing the two members of the handle, the movable member moves toward the fixed member and forces the plunger into the barrel of the syringe. Thus, the handle of such a syringe allows the force provided by a hand squeeze to be applied to the plunger of the syringe rather than the lesser amount of force that would otherwise be provided by use of a thumb to force the plunger into the syringe. Nonetheless, these fluid delivery devices may be difficult to use when the injection of high viscosity fluids is required, which may cause physical or mental discomfort to a patient into whom the fluid is being injected.
Some fluid delivery devices provide leverage to assist a user in forcing a plunger into or out of a syringe barrel. Examples of such devices are provided in U.S. Pat. No. 6,030,368, issued to Anwar et al. (hereinafter “the '368 Patent”) and U.S. Pat. No. 4,737,151, issued to Clement et al. (hereinafter “the '151 Patent). The devices of the '368 and '151 Patents each include three pivot points to provide the desired amount of leverage: a first pivot point connecting a handle member to a plunger; a second pivot point connecting the handle member to a base member; and a third pivot point connecting the base member to a syringe barrel. While the base members of these devices are configured to be supported upon a table top or other flat surface, the generally straight handle members of these devices are configured to receive a downward force by a user, which is transferred to the plunger. As a user need only grip and move the handle member of such a device to move the plunger, the user can apply more force to the handle than that provided by a squeeze of the hand. Nonetheless, due to the manner in which the increased amount of force is applied, it is difficult for a user to make fine adjustments when injecting fluid into a body or extracting fluid therefrom.
Accordingly, there is a need for a fluid delivery apparatus that converts a small amount of controllable force, such as that provided by a squeeze of a hand, to a syringe plunger to faciliate movement of the plunger through a syringe barrel.